750 lines
14 KiB
C
750 lines
14 KiB
C
/* ET-trees data structure implementation.
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Contributed by Pavel Nejedly
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Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
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This file is part of the libiberty library.
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Libiberty is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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Libiberty is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with libiberty; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA.
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The ET-forest structure is described in:
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D. D. Sleator and R. E. Tarjan. A data structure for dynamic trees.
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J. G'omput. System Sci., 26(3):362 381, 1983.
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*/
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "et-forest.h"
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#include "alloc-pool.h"
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/* We do not enable this with ENABLE_CHECKING, since it is awfully slow. */
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#undef DEBUG_ET
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#ifdef DEBUG_ET
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#include "basic-block.h"
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#endif
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/* The occurrence of a node in the et tree. */
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struct et_occ
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{
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struct et_node *of; /* The node. */
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struct et_occ *parent; /* Parent in the splay-tree. */
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struct et_occ *prev; /* Left son in the splay-tree. */
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struct et_occ *next; /* Right son in the splay-tree. */
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int depth; /* The depth of the node is the sum of depth
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fields on the path to the root. */
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int min; /* The minimum value of the depth in the subtree
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is obtained by adding sum of depth fields
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on the path to the root. */
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struct et_occ *min_occ; /* The occurrence in the subtree with the minimal
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depth. */
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};
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static alloc_pool et_nodes;
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static alloc_pool et_occurrences;
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/* Changes depth of OCC to D. */
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static inline void
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set_depth (struct et_occ *occ, int d)
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{
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if (!occ)
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return;
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occ->min += d - occ->depth;
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occ->depth = d;
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}
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/* Adds D to the depth of OCC. */
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static inline void
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set_depth_add (struct et_occ *occ, int d)
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{
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if (!occ)
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return;
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occ->min += d;
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occ->depth += d;
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}
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/* Sets prev field of OCC to P. */
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static inline void
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set_prev (struct et_occ *occ, struct et_occ *t)
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{
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#ifdef DEBUG_ET
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gcc_assert (occ != t);
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#endif
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occ->prev = t;
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if (t)
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t->parent = occ;
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}
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/* Sets next field of OCC to P. */
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static inline void
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set_next (struct et_occ *occ, struct et_occ *t)
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{
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#ifdef DEBUG_ET
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gcc_assert (occ != t);
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#endif
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occ->next = t;
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if (t)
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t->parent = occ;
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}
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/* Recompute minimum for occurrence OCC. */
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static inline void
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et_recomp_min (struct et_occ *occ)
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{
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struct et_occ *mson = occ->prev;
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if (!mson
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|| (occ->next
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&& mson->min > occ->next->min))
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mson = occ->next;
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if (mson && mson->min < 0)
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{
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occ->min = mson->min + occ->depth;
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occ->min_occ = mson->min_occ;
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}
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else
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{
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occ->min = occ->depth;
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occ->min_occ = occ;
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}
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}
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#ifdef DEBUG_ET
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/* Checks whether neighborhood of OCC seems sane. */
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static void
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et_check_occ_sanity (struct et_occ *occ)
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{
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if (!occ)
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return;
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gcc_assert (occ->parent != occ);
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gcc_assert (occ->prev != occ);
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gcc_assert (occ->next != occ);
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gcc_assert (!occ->next || occ->next != occ->prev);
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if (occ->next)
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{
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gcc_assert (occ->next != occ->parent);
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gcc_assert (occ->next->parent == occ);
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}
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if (occ->prev)
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{
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gcc_assert (occ->prev != occ->parent);
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gcc_assert (occ->prev->parent == occ);
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}
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gcc_assert (!occ->parent
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|| occ->parent->prev == occ
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|| occ->parent->next == occ);
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}
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/* Checks whether tree rooted at OCC is sane. */
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static void
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et_check_sanity (struct et_occ *occ)
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{
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et_check_occ_sanity (occ);
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if (occ->prev)
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et_check_sanity (occ->prev);
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if (occ->next)
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et_check_sanity (occ->next);
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}
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/* Checks whether tree containing OCC is sane. */
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static void
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et_check_tree_sanity (struct et_occ *occ)
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{
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while (occ->parent)
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occ = occ->parent;
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et_check_sanity (occ);
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}
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/* For recording the paths. */
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/* An ad-hoc constant; if the function has more blocks, this won't work,
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but since it is used for debugging only, it does not matter. */
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#define MAX_NODES 100000
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static int len;
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static void *datas[MAX_NODES];
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static int depths[MAX_NODES];
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/* Records the path represented by OCC, with depth incremented by DEPTH. */
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static int
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record_path_before_1 (struct et_occ *occ, int depth)
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{
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int mn, m;
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depth += occ->depth;
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mn = depth;
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if (occ->prev)
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{
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m = record_path_before_1 (occ->prev, depth);
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if (m < mn)
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mn = m;
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}
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fprintf (stderr, "%d (%d); ", ((basic_block) occ->of->data)->index, depth);
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gcc_assert (len < MAX_NODES);
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depths[len] = depth;
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datas[len] = occ->of;
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len++;
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if (occ->next)
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{
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m = record_path_before_1 (occ->next, depth);
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if (m < mn)
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mn = m;
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}
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gcc_assert (mn == occ->min + depth - occ->depth);
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return mn;
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}
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/* Records the path represented by a tree containing OCC. */
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static void
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record_path_before (struct et_occ *occ)
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{
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while (occ->parent)
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occ = occ->parent;
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len = 0;
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record_path_before_1 (occ, 0);
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fprintf (stderr, "\n");
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}
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/* Checks whether the path represented by OCC, with depth incremented by DEPTH,
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was not changed since the last recording. */
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static int
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check_path_after_1 (struct et_occ *occ, int depth)
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{
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int mn, m;
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depth += occ->depth;
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mn = depth;
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if (occ->next)
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{
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m = check_path_after_1 (occ->next, depth);
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if (m < mn)
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mn = m;
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}
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len--;
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gcc_assert (depths[len] == depth && datas[len] == occ->of);
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if (occ->prev)
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{
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m = check_path_after_1 (occ->prev, depth);
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if (m < mn)
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mn = m;
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}
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gcc_assert (mn == occ->min + depth - occ->depth);
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return mn;
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}
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/* Checks whether the path represented by a tree containing OCC was
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not changed since the last recording. */
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static void
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check_path_after (struct et_occ *occ)
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{
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while (occ->parent)
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occ = occ->parent;
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check_path_after_1 (occ, 0);
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gcc_assert (!len);
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}
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#endif
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/* Splay the occurrence OCC to the root of the tree. */
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static void
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et_splay (struct et_occ *occ)
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{
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struct et_occ *f, *gf, *ggf;
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int occ_depth, f_depth, gf_depth;
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#ifdef DEBUG_ET
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record_path_before (occ);
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et_check_tree_sanity (occ);
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#endif
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while (occ->parent)
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{
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occ_depth = occ->depth;
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f = occ->parent;
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f_depth = f->depth;
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gf = f->parent;
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if (!gf)
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{
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set_depth_add (occ, f_depth);
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occ->min_occ = f->min_occ;
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occ->min = f->min;
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if (f->prev == occ)
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{
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/* zig */
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set_prev (f, occ->next);
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set_next (occ, f);
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set_depth_add (f->prev, occ_depth);
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}
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else
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{
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/* zag */
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set_next (f, occ->prev);
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set_prev (occ, f);
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set_depth_add (f->next, occ_depth);
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}
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set_depth (f, -occ_depth);
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occ->parent = NULL;
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et_recomp_min (f);
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#ifdef DEBUG_ET
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et_check_tree_sanity (occ);
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check_path_after (occ);
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#endif
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return;
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}
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gf_depth = gf->depth;
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set_depth_add (occ, f_depth + gf_depth);
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occ->min_occ = gf->min_occ;
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occ->min = gf->min;
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ggf = gf->parent;
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if (gf->prev == f)
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{
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if (f->prev == occ)
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{
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/* zig zig */
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set_prev (gf, f->next);
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set_prev (f, occ->next);
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set_next (occ, f);
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set_next (f, gf);
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set_depth (f, -occ_depth);
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set_depth_add (f->prev, occ_depth);
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set_depth (gf, -f_depth);
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set_depth_add (gf->prev, f_depth);
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}
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else
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{
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/* zag zig */
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set_prev (gf, occ->next);
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set_next (f, occ->prev);
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set_prev (occ, f);
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set_next (occ, gf);
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set_depth (f, -occ_depth);
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set_depth_add (f->next, occ_depth);
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set_depth (gf, -occ_depth - f_depth);
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set_depth_add (gf->prev, occ_depth + f_depth);
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}
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}
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else
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{
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if (f->prev == occ)
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{
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/* zig zag */
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set_next (gf, occ->prev);
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set_prev (f, occ->next);
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set_prev (occ, gf);
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set_next (occ, f);
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set_depth (f, -occ_depth);
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set_depth_add (f->prev, occ_depth);
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set_depth (gf, -occ_depth - f_depth);
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set_depth_add (gf->next, occ_depth + f_depth);
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}
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else
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{
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/* zag zag */
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set_next (gf, f->prev);
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set_next (f, occ->prev);
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set_prev (occ, f);
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set_prev (f, gf);
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set_depth (f, -occ_depth);
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set_depth_add (f->next, occ_depth);
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set_depth (gf, -f_depth);
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set_depth_add (gf->next, f_depth);
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}
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}
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occ->parent = ggf;
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if (ggf)
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{
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if (ggf->prev == gf)
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ggf->prev = occ;
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else
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ggf->next = occ;
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}
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et_recomp_min (gf);
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et_recomp_min (f);
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#ifdef DEBUG_ET
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et_check_tree_sanity (occ);
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#endif
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}
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#ifdef DEBUG_ET
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et_check_sanity (occ);
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check_path_after (occ);
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#endif
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}
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/* Create a new et tree occurrence of NODE. */
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static struct et_occ *
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et_new_occ (struct et_node *node)
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{
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struct et_occ *nw;
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if (!et_occurrences)
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et_occurrences = create_alloc_pool ("et_occ pool", sizeof (struct et_occ), 300);
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nw = pool_alloc (et_occurrences);
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nw->of = node;
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nw->parent = NULL;
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nw->prev = NULL;
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nw->next = NULL;
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nw->depth = 0;
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nw->min_occ = nw;
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nw->min = 0;
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return nw;
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}
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/* Create a new et tree containing DATA. */
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struct et_node *
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et_new_tree (void *data)
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{
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struct et_node *nw;
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if (!et_nodes)
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et_nodes = create_alloc_pool ("et_node pool", sizeof (struct et_node), 300);
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nw = pool_alloc (et_nodes);
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nw->data = data;
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nw->father = NULL;
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nw->left = NULL;
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nw->right = NULL;
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nw->son = NULL;
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nw->rightmost_occ = et_new_occ (nw);
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nw->parent_occ = NULL;
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return nw;
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}
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/* Releases et tree T. */
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void
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et_free_tree (struct et_node *t)
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{
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while (t->son)
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et_split (t->son);
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if (t->father)
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et_split (t);
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pool_free (et_occurrences, t->rightmost_occ);
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pool_free (et_nodes, t);
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}
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/* Releases et tree T without maintaining other nodes. */
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void
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et_free_tree_force (struct et_node *t)
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{
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pool_free (et_occurrences, t->rightmost_occ);
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if (t->parent_occ)
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pool_free (et_occurrences, t->parent_occ);
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pool_free (et_nodes, t);
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}
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/* Release the alloc pools, if they are empty. */
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void
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et_free_pools (void)
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{
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free_alloc_pool_if_empty (&et_occurrences);
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free_alloc_pool_if_empty (&et_nodes);
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}
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/* Sets father of et tree T to FATHER. */
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void
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et_set_father (struct et_node *t, struct et_node *father)
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{
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struct et_node *left, *right;
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struct et_occ *rmost, *left_part, *new_f_occ, *p;
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/* Update the path represented in the splay tree. */
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new_f_occ = et_new_occ (father);
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rmost = father->rightmost_occ;
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et_splay (rmost);
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left_part = rmost->prev;
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p = t->rightmost_occ;
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et_splay (p);
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set_prev (new_f_occ, left_part);
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set_next (new_f_occ, p);
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p->depth++;
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p->min++;
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et_recomp_min (new_f_occ);
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set_prev (rmost, new_f_occ);
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if (new_f_occ->min + rmost->depth < rmost->min)
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{
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rmost->min = new_f_occ->min + rmost->depth;
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rmost->min_occ = new_f_occ->min_occ;
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}
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t->parent_occ = new_f_occ;
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/* Update the tree. */
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t->father = father;
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right = father->son;
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if (right)
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left = right->left;
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else
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left = right = t;
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left->right = t;
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right->left = t;
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t->left = left;
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t->right = right;
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father->son = t;
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#ifdef DEBUG_ET
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et_check_tree_sanity (rmost);
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record_path_before (rmost);
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#endif
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}
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/* Splits the edge from T to its father. */
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void
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et_split (struct et_node *t)
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{
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struct et_node *father = t->father;
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struct et_occ *r, *l, *rmost, *p_occ;
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/* Update the path represented by the splay tree. */
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rmost = t->rightmost_occ;
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et_splay (rmost);
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for (r = rmost->next; r->prev; r = r->prev)
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continue;
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et_splay (r);
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r->prev->parent = NULL;
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p_occ = t->parent_occ;
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et_splay (p_occ);
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t->parent_occ = NULL;
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l = p_occ->prev;
|
|
p_occ->next->parent = NULL;
|
|
|
|
set_prev (r, l);
|
|
|
|
et_recomp_min (r);
|
|
|
|
et_splay (rmost);
|
|
rmost->depth = 0;
|
|
rmost->min = 0;
|
|
|
|
pool_free (et_occurrences, p_occ);
|
|
|
|
/* Update the tree. */
|
|
if (father->son == t)
|
|
father->son = t->right;
|
|
if (father->son == t)
|
|
father->son = NULL;
|
|
else
|
|
{
|
|
t->left->right = t->right;
|
|
t->right->left = t->left;
|
|
}
|
|
t->left = t->right = NULL;
|
|
t->father = NULL;
|
|
|
|
#ifdef DEBUG_ET
|
|
et_check_tree_sanity (rmost);
|
|
record_path_before (rmost);
|
|
|
|
et_check_tree_sanity (r);
|
|
record_path_before (r);
|
|
#endif
|
|
}
|
|
|
|
/* Finds the nearest common ancestor of the nodes N1 and N2. */
|
|
|
|
struct et_node *
|
|
et_nca (struct et_node *n1, struct et_node *n2)
|
|
{
|
|
struct et_occ *o1 = n1->rightmost_occ, *o2 = n2->rightmost_occ, *om;
|
|
struct et_occ *l, *r, *ret;
|
|
int mn;
|
|
|
|
if (n1 == n2)
|
|
return n1;
|
|
|
|
et_splay (o1);
|
|
l = o1->prev;
|
|
r = o1->next;
|
|
if (l)
|
|
l->parent = NULL;
|
|
if (r)
|
|
r->parent = NULL;
|
|
et_splay (o2);
|
|
|
|
if (l == o2 || (l && l->parent != NULL))
|
|
{
|
|
ret = o2->next;
|
|
|
|
set_prev (o1, o2);
|
|
if (r)
|
|
r->parent = o1;
|
|
}
|
|
else
|
|
{
|
|
ret = o2->prev;
|
|
|
|
set_next (o1, o2);
|
|
if (l)
|
|
l->parent = o1;
|
|
}
|
|
|
|
if (0 < o2->depth)
|
|
{
|
|
om = o1;
|
|
mn = o1->depth;
|
|
}
|
|
else
|
|
{
|
|
om = o2;
|
|
mn = o2->depth + o1->depth;
|
|
}
|
|
|
|
#ifdef DEBUG_ET
|
|
et_check_tree_sanity (o2);
|
|
#endif
|
|
|
|
if (ret && ret->min + o1->depth + o2->depth < mn)
|
|
return ret->min_occ->of;
|
|
else
|
|
return om->of;
|
|
}
|
|
|
|
/* Checks whether the node UP is an ancestor of the node DOWN. */
|
|
|
|
bool
|
|
et_below (struct et_node *down, struct et_node *up)
|
|
{
|
|
struct et_occ *u = up->rightmost_occ, *d = down->rightmost_occ;
|
|
struct et_occ *l, *r;
|
|
|
|
if (up == down)
|
|
return true;
|
|
|
|
et_splay (u);
|
|
l = u->prev;
|
|
r = u->next;
|
|
|
|
if (!l)
|
|
return false;
|
|
|
|
l->parent = NULL;
|
|
|
|
if (r)
|
|
r->parent = NULL;
|
|
|
|
et_splay (d);
|
|
|
|
if (l == d || l->parent != NULL)
|
|
{
|
|
if (r)
|
|
r->parent = u;
|
|
set_prev (u, d);
|
|
#ifdef DEBUG_ET
|
|
et_check_tree_sanity (u);
|
|
#endif
|
|
}
|
|
else
|
|
{
|
|
l->parent = u;
|
|
|
|
/* In case O1 and O2 are in two different trees, we must just restore the
|
|
original state. */
|
|
if (r && r->parent != NULL)
|
|
set_next (u, d);
|
|
else
|
|
set_next (u, r);
|
|
|
|
#ifdef DEBUG_ET
|
|
et_check_tree_sanity (u);
|
|
#endif
|
|
return false;
|
|
}
|
|
|
|
if (0 >= d->depth)
|
|
return false;
|
|
|
|
return !d->next || d->next->min + d->depth >= 0;
|
|
}
|